Ignition timing control

ABSTRACT

A vacuum motor, connected to the distributor to control ignition timing, has one diaphragm responsive to a first, full manifold vacuum, signal to provide limited initial advance of ignition timing and another diaphragm responsive to a second induction vacuum signal, originating at a port traversed by the throttle, to provide additional advance of the timing. A valve controlling exhaust gas recirculation also responds to the second signal, and ignition timing is thus coordinated with exhaust gas recirculation.

United States Patent 1191 Thornburgh Oct. 28, 1975 IGNITION TIMING CONTROL 3,187,640 6/1965 Young et a1. 92/48 1751 Inventor: William Thomburgh, Rochester, 315515; 111323 1 5,222.if;1:11:31:3:1::::::::...:1J1: 33/13 Mich 3,515,105 6/1970 $661615 123/117 A 73 Assigneez General Motors Corporation, 3,780,713 l2/l973 Julian 123/117 A Detroit, Mich. Primary Examiner-Charles .1. Myhre [22] Flled: 1974 Assistant Examiner-Tony Argenbright 1 AppL NOJ 519,529 Attorney, Agent, or Firm-C. K. Veenstra 57 ABSTRACT [52] US. Cl 123/117 A; 91/183; 92/48; 1

92 /6 4 A vacuum motor, connected to the d1str1butor to con- 51 Int. (:1. F02P 5/02; FOlB 1/00 ignition i has one dijlphragm P Y F [58] Field of Search..... 123/117 A, 117 R, 146.5 A; Y F fun mamfdd Y PP f l Pmvde F 92/48, 63, 64; 91/170 R 183 1n1t1al advance of Ignition tim ng and another d aphragm responslve to a second 1nduct1on vacuum 51g- [56] References Cited nal, rarigirgajting a: adport trazetgsecti by this tilgottlel) to prov1 e a mom a vance o' e 1m1ng. ve c n- UNITED STATES PATENTS trolling exhaust gas recirculation also responds to the Udale A econd ignal and ignition is thus coordinated 2,768,818 10/1956 Egerenm. 92/48 x with exhaust gas recirculation. 3,043,285 7/1962 Bettom 123/117 A 3,077,186 2/1963 De Beaubien et a1. 92/48 2 Claims, 1 Drawing Figure US. Patent Oct. 28, 1975 ADVANCE IGNITION TIMING CONTROL This invention relates to ignition timing control and, more particularly, to a vacuum motor, connected to the distributor to control ignition timing, which has one ina headed portion 28.

Diaphragm 18 is received between a pair of retainer plates 30 and 32, and their assembly is secured in a guide member 34. A link 36 is secured to connector 26 ptteigtiplgtpliessiiire I'eSPOtlISIK p g Provldmg f (as by staking as at 38) and is slidably received in guide vance o t e tlmmg and zfnother (113' 34. Link 36 extends to a distributor 40 to control igniphragm which responds to another induction pressure tion timing therein signal to provide additional advance of the timing.

The ignition timing control provided by this inven- A boot 42 S,1rrOundS P I 26 and recwed m tion is preferably used with an exhaust gas recirculation a cetitral, Opening 44 of dmder to f 8 flmd (EGR) system. Such systems have been proposed and munufailon beiween i twqsldes of dmder 16 whlle used to reduce formation and emission of oxides of nipermmmg reclprocauon of lmk 36 Connector trogen from internal combustion engines. In the system A 46 defined between housmg 20 and shown in US. Pat. No. 3,641,989, for example, a valve phragm 18.15 open to the atmosphere through a controls recirculation of exhaust gases in accordance of openmgs.4s' A chamber defined between with the vacuum signal created at an induction passage vlder 16 and dlaphragm 14 also open to the 2 port which is traversed by the edge of the throttle. That sphere through a phirilhty of apertures 52 extendmg system thus prevents recirculation during closed and through nm of dlvlder chamber 54 defined wide open throttle operation and permits recirculation between R i and dlvlder 15 connected of exhaust gases at varying rates during part throttle through a fitting 56 wlth a tap .58 opening from the eneration gme air 1nduct1on passage 60. A chamber 64 defined In some applications of that system, it is considered between daPhragm 14 and Gov/Fr 12 1S connefzted y a desirable to advance the ignition timing a limited initial fitting 66 a port 68 Opemng from the mductmn amount of about 15, for example, whenever the engine passage adjacent the edge 70 of throttle is operating with a manifold va uu greater th per In operation, with the engine running with a vacuum haps about 4 Hg and to advance the ignition timing an o more than, for example, 4 Hg, diaphragm 18 is additional amount up to a total of about 28", for exammoved rightwardly until retainer plate engages diple, as the vacuum signal delivered to the EGR valve Videl' 6- During this motion, guide 34 engages connecincreases to perhaps 8 I-Ig. tor 26 and moves link 36 rightwardly to advance the ig- This invention provides an ignition timing control 30 nition timing perhaps 15. With throttle 62 closed as which advances the timing in the desired manner. In a shown, port 68 senses atmospheric pressure and diacontrol provided by this invention, a vacuum motor, phragm 14 moves only with diaphragm 18. As throttle connected to the distributor to control ignition timing, 62 is opened, however, port 68 senses an increasing has one diaphragm responsive to a first, full manifold proportion of the manifold vacuum downstream vacuum, signal to provide limited initial advance of igthereof, and diaphragm 14 is moved rightwardly. At nition timing and another diaphragm responsive to a this time, link 36 slides through guide 34 to further adsecond induction vacuum signal, originating at a port vance the spark. Rightward motion of diaphragm 14 traversed by the throttle, to provide additional advance continues until retainer 22 engages cover 12. This may of the timing. A valve controlling exhaust gas recirculaoccur when port 68 senses a vacuum of, for example, tion also responds to the second signal, and ignition 8 Hg; at that time, the ignition timing may have been timing is thus coordinated with exhaustgas recirculaadvanced a total of perhaps 28. The following table tion. I sets forth the ignition timing advance (in degrees) pro- The details as well as other features and advantages vided at varying vacuum levels (in inches of Mercury) of this invention are set forth in the remainder of the sensed by tap 58 and port 68:

Tap Port Port Fort Port Port Vac Vac Adv Vac Adv Vac Adv Vac Adv Vac Adv 4 0 15. 2 15. 4 19.5 6 0 15. 2 1s. 4 20. 6 24. 8 0 15. 2 15. 4 20. 6 25. 8 25 10 0 15. 2 15. 4 19.5 6 24. 8 27. 12 0 15.5 2 15.5 4 19.5 6 24.5 8 27. 14 0 l6, 2 16. 4 20. 6 24.5 8 28. 16 0 16. 2 16. 4 20. 6 25. 8 28. 18 0 16. 2 16. 4 20. 6 25. 8 2s. 20 0 16. 2 l6, 4 20. 6 25v 8 28. 22 0 16. 2 l6. 4 20.5 6 25. 8 28. 24 0 16 2 16. 4 20.5 6 25. 8 2s.

specification and in the drawing which shows a sec- The vacuum signal created at port 68 also is delivtional view of a distributor vacuum motor made in ac-' ered to an exhaust gas recirculation control valve 72. cordance with this invention and schematically illus- Valve 72 has a diaphragm 74 which is received betrates its connections with the induction passage and an tween a cover 76 and a support housing 78 and is conassociated EGR system. nected to a stem 80. Stem 80 extends through a sealing Referring to the drawing, a vacuum motor 10 comunit 82 into a base member 84 and is connected to a prises a cover 12, a diaphragm 14, a divider 16, a dia- 65 valve pintle 86. Valve pintle 86 is associated with a phragm 18, and a support housing 20. Diaphragm 14 is received between a pair of retainer plates 22 and 24, and their assembly is secured to a connector 26 having valve seat 88 disposed about the inlet 90 of base member 84. Inlet 90 receives exhaust gases from a portion of the engine exhaust system 92. Base member 84 has an outlet 94 connected by a passage 96 to induction passage 60 downstream of throttle 62.

In operation, with throttle 62 closed as shown, the chamber 98 defined between diaphragm 74 and cover 76 senses the atmospheric pressure at port 68 upstream of throttle 62, and a spring 100 holds valve pintle 86 against valve seat 88. As throttle 62 is opened and its upstream edge 70 traverses port 68, an increasing proportion of the manifold vacuum present downstream of throttle 62 is transmitted to chamber 98. Diaphragm 74 then lifts pintle 86 to permit recirculation of exhaust gases from exhaust system 92 to induction passage 60 at an increasing rate. Because the same source, port 68, is used for the vacuum signal controlling both EGR valve 72 and vacuum motor 10, ignition timing is advanced as the rate of exhaust gas recirculation is increased.

It will be appreciated, of course, that as throttle 62 reaches the wide open position, the manifold vacuum decreases and approaches zero. At such time, spring 100 forces valve pintle 86 back into engagement with valve 88 to prevent recirculation of exhaust gases and spring 102 in vacuum motor returns diaphragms l4 and 18, connector 26 and link 36 to the position shown to retard the ignition timing from its advanced state.

It also will be appreciated that diaphragms 14 and 18 may have different effective areas if identical response to variations in their respective vacuum signals is not desired.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An ignition timing control comprising a vacuum motor having first and second diaphragms, a divider between said diaphragms and defining an atmospheric pressure chamber with said first diaphragm and a manifold vacuum chamber with said second diaphragm, a cover adjacent and defining a ported vacuum chamber with said first diaphragm, and an operating link secured to said first diaphragm and having an enlarged portion, said second diaphragm having a central opening slidably receiving said link and being engageable with said enlarged portion of said link whereby upon application of a vacuum signal to said manifold vacuum chamber said second diaphragm may engage said enlarged portion of said link to move said link a limited amount and whereby upon application of a vacuum signal to said ported vacuum chamber said first diaphragm may move said link an additional amount independently of said second diaphragm.

2. In an internal combustion engine having an induction passage for air flow to the engine, a throttle disposed in said passage and rotatable between closed and open positions for controlling air flow therethrough, an exhaust system, a recirculation passage extending from said exhaust system to said induction passage, a valve disposed in said recirculation passage and movable between closed and open positions for controlling exhaust gas flow therethrough, a control disphragm for moving said valve, and an ignition system: an ignition timing control comprising a vacuum motor having first and second diaphragms, a divider between said diaphragms and defining an atmospheric pressure chamber with said first diaphragm and a manifold vacuum chamber with said second diaphragm, a cover adjacent and defining a ported vacuum chamber with said first diaphragm, an operating link secured to said first diaphragm, said second diaphragm having a central opening slidably receiving said link and being engageable with an enlarged portion of said link, means including a tap opening from said induction passage downstream of said throttle for applying a manifold vacuum signal to said manifold vacuum chamber to cause said second diaphragm to engage said enlarged portion of said link and move said link a limited amount for advancing the ignition timing, and means including a port opening from said induction passage upstream of said throttle when said throttle is in said closed position and traversed by said throttle as said throttle is rotated for applying a ported vacuum signal to said ported vacuum chamber and to said control diaphragm to cause said first diaphragm to move said link an additional amount independently of said second diaphragm for further advancing the ignition timing and to cause said control diaphragm to simultaneously move said valve for increasing exhaust gas flow through said recirculation passage. 

1. An ignition timing control comprising a vacuum motor having first and second diaphragms, a divider between said diaphragms and defining an atmospheric pressure chamber with said first diaphragm and a manifold vacuum chamber with said second diaphragm, a cover adjacent and defining a ported vacuum chamber with said first diaphragm, and an operating link secured to said first diaphragm and having an enlarged portion, said second diaphragm having a central opening slidably receiving said link and being engageable with said enlarged portion of said link whereby upon application of a vacuum signal to said manifold vacuum chamber said second diaphragm may engage said enlarged portion of said link to move said link a limited amount and whereby upon application of a vacuum signal to said ported vacuum chamber said first diaphragm may move said link an additional amount independently of said second diaphragm.
 2. In an internal combustion engine having an induction passage for air flow to the engine, a throttle disposed in said passage and rotatable between closed and open positions for controlling air flow therethrough, an exhaust system, a recirculation passage extending from said exhaust system to said induction passage, a valve disposed in said recirculation passage and movable between closed and open positions for controlling exhaust gas flow therethrough, a control disphragm for moving said valve, and an ignition system: an ignition timing control comprising a vacuum motor having first and second diaphragms, a divider between said diaphragms and defining an atmospheric pressure chamber with said first diaphragm and a manifold vacuum chamber with said second diaphragm, a cover adjacent and defining a ported vacuum chamber with said first diaphragm, an operating link secured to said first diaphragm, said second diaphragm having a central opening slidably receiving said link and being engageable with an enlarged portion of said link, means including a tap opening from said induction passage downstream of said throttle for applying a manifold vacuum signal to said manifold vacuum chamber to cause said second diaphragm to engage said enlarged portion of said link and move said link a limited amount for advancing the ignition timing, and means including a port opening from said induction passage upstream of said throttle when said throttle is in said closed position and traversed by said throttle as said throttle is rotated for applying a ported vacuum signal to said ported vacuum chamber and to said control diaphragm to cause said first diaphragm to move said link an additional amount independently of said second diaphragm for further advancing the ignition timing and to cause said control diaphragm to simultaneously move said valve for increasing exhaust gas flow through said recirculation passage. 